1. Field of the Invention
The present invention relates to a high pressure condenser for a magnetron, and more particularly to a high pressure condenser for a magnetron, in which a dielectric ceramic is divided into a plurality of portions having an arch shape and electrodes are formed on the side surfaces of the plural portions of the dielectric ceramic.
2. Description of the Related Art
Generally, magnetrons are apparatuses for generating and outputting microwaves, installed in a microwave oven or etc., and include a high pressure condenser for inputting high voltage therethrough.
FIG. 1 is a cross-sectional view of a conventional magnetron. The conventional magnetron comprises an anode unit including vanes 12 and straps 13 forming a resonance circuit when anode voltage and anode current having constant quantities are applied to the magnetron, a cathode unit 14 placed inside the anode unit for generating a large quantity of thermal electrons and generating microwaves in a space where the cathode unit 14 acts with ends of the vanes 12, an antenna 15 for transmitting the microwaves generated in the acting space to the outside, a plurality of cooling pins 16 installed on the outer periphery of the anode unit for radiating heat converted from residual energy, which is not transformed into the microwaves, yokes 17 and 18 for protecting and supporting the anode unit and the cooling pins 16 and guiding external air to the cooling pins 16, upper and lower permanent magnets 19 and 20 respectively placed on lower and upper surfaces of the yokes 17 and 18 for constituting a closed magnetic circuit, and a filter box 22 including an LC filter 21 for removing high-frequency radiation noise.
The anode unit includes an anode main body 11 having a cylindrical shape, a plurality of the vanes 12 installed in the anode main body 11, and the straps 13 passing through the vanes 12 for constituting the resonance circuit between the vanes 12 and the straps 13.
The filter box 22 includes coils and ferrites for providing inductance to the LC filter 21, and a high pressure condenser 23 for inputting high voltage to the magnetron and providing capacitance to the LC filter 21 is installed on one side surface of the filter box 22.
FIG. 2 is a cross-sectional view of a conventional high pressure condenser for a magnetron, and FIG. 3 is an exploded perspective view of the conventional high pressure condenser.
As shown in FIGS. 2 and 3, the conventional high pressure condenser 23 comprises a dielectric ceramic 31, a ground metal 37, a lower cover 38, metal caps 39 and 40, central conductors 41 and 42, an upper cover 43, insulating tubes 44 and 45, and insulating fillers 46 and 47.
A pair of through holes 32 and 33 are formed through the dielectric ceramic 31, a pair of separation electrodes 34 and 35 are installed on the upper surface of the dielectric ceramic 31, and a common electrode 36 is installed on the lower surface of the dielectric ceramic 31.
A plurality of connection holes 37b for fixing the ground metal 37 to the filter box 22 are formed through four corners of a plate unit 37a having a rectangular shape of the ground metal 37. A protuberance 37d connected to the common electrode 36 is formed on the center of the plate unit 37a, and a through hole 37c having an oval shape is formed through the protuberance 37d of the plate unit 37a. 
The metal caps 39 and 40 are bonded to the central conductors 41 and 42 and connected to the separation electrodes 34 and 35 so that the central conductors 41 and 42 and the separation electrodes 34 and 35 are connected.
Taps 41a and 42b are respectively formed integrally with the upper ends of the central conductors 41 and 42, and the central conductors 41 and 42 sequentially pass through the metal caps 39 and 40, the through holes 32 and 33 of the dielectric ceramic 31, and the oval through holes 37c of the ground metal 37, and are soldered to the metal caps 39 and 40.
The central conductors 41 and 42 are covered with the insulating tubes 44 and 45 made of a material having elasticity, such as silicon.
The insulating fillers 46 and 47 are closer to the central conductors 41 and 42 than to the dielectric ceramic 31. The insulating fillers 46 and 47 are exfoliated from the dielectric ceramic 31 due to residual stress of the insulating fillers 46 and 47 or stress generated by the variation in temperature, thereby depreciating withstand voltage. The insulating tubes 44 and 45 made of an elastic material, which coat the central conductors 41 and 42, prevent the above depreciation of the withstand voltage.
The lower cover 38 is attached to the ground metal 37, thereby surrounding the lower parts of the central conductors 41 and 42 coated with the insulating tubes 44 and 45.
The upper cover 43 is attached to the ground metal 37, thereby surrounding the dielectric ceramic 31, the metal caps 39 and 40, and the upper parts of the central conductors 41 and 42.
The high pressure condenser 23 is installed such that the inside of the high pressure condenser 23 is vertically divided by the ground metal 37, the dielectric ceramic 31 and the metal caps 39 and 40. The insulating fillers 46 and 47 are respectively injected into the high pressure condenser 23 through an opening of the upper cover 43 and an opening of the lower cover 38.
The insulating filler 46, which is injected into the high pressure condenser 23 through the opening of the upper cover 43, surrounds the outer surfaces of the dielectric ceramic 31 and the metal caps 39 and 40 and the upper parts of the central conductors 41 and 42, and the insulating filler 47, which is injected into the high pressure condenser 23 through the opening of the lower cover 38, fills the insides of the dielectric ceramic 31 and the metal caps 39 and 40 and surrounds the insulating tubes 44 and 45.
Since the inside of the high pressure condenser 23 is vertically divided so that the insulating fillers 46 and 47 are injected into the high pressure condenser 23 by two steps, and is hardened, the conventional high pressure condenser 23 is disadvantageous in that time and costs taken to fill the high pressure condenser 23 with the insulating fillers 46 and 47 are increased, a step for soldering the metal caps 39 and 40 for connecting the central conductors 41 and 42 and the separation electrodes 34 and 35 is required, the central conductors 41 and 42 have complicated structures due to the attachment between the central conductors 41 and 42 and the metal caps 39 and 40, and the dielectric ceramic 31 and the insulating fillers 46 and 47 are interposed between the central conductors 41 and 42.